The nests of Cadeguala albopilosa (Spinola, 1851), Diphaglossa gayi Spinola, 1851, Ptiloglossa tarsata (Friese, 1900), Ptiloglossa matutina (Schrottky, 1904) and Zikanapis tucumana (Moure, 1945) (Colletidae, Diphaglossinae) from Argentina and Chile are described herein. They show similar features to those of other Diphaglossinae: they consist of a main tunnel, cells disposed radially, isolated or in pairs, and connected to the main tunnel by laterals ones. Main tunnels are mostly vertical in species nesting in soil surface but horizontal to inclined in D. gayi, which nests in banks. Cells are vertical with curved necks. The cells of C. albopilosa show less curved necks (less than 90°), whereas in the remaining four species the cell neck is highly curved (90° or more). Cells of P. tarsata have a spiral earthen closure and a wad cottonlike material, whereas in P. matutina only had the last one. In the remaining studied species any type of closure were found. Cocoons of C. albopilosa and P. tarsata are coriaceous showing a closure composed of three disks. Zikanapis tucumana and possibly P. matutina showed dim-light foraging. The remaining species are diurnal. The climate in their nesting sites is highly diverse, ranging from 8°C to 20°C in mean annual temperature, and from 250 mm to 3000 mm in mean annual precipitation. Only C. albopilosa and, to a lesser extent, Z. tucumana nested gregariously. Zikanapis tucumana and P. tarsata were observed visiting flowers of Solanum.

How species similarity changes between habitats along environmental gradients is still a central challenge in ecological studies. We assessed whether marsh plant characteristics are associated with geographic changes in environmental conditions and whether there are environmental factors associated with marsh−inland dissimilarity in species composition. Field samples of vegetation were collected at 6 sites along the SW Atlantic to determine plant characteristics (cover, tallness, richness and α-diversity), and marsh-inland dissimilarity (β-diversity) in species composition was calculated. PERMANOVA analysis showed that plant assemblage changes among sites. Forward stepwise multiple regression analysis showed that in lower marsh, plant cover increased in association with tidal range and decreased in association with salinity. In the high marsh, plant cover decreased in association with tidal range, salinity and with minimum temperatures. Plant richness increased in association with tidal range and with marsh area, while α-diversity decreased in association with precipitation and increased with salinity. Beta-diversity, estimated by SIMPER analysis, increased in association with precipitation and decreased with salinity and daily thermal amplitude. We present evidence that there is an increase in α-diversity but a decrease in β-diversity with environmental severity among co-specific marshes distributed along the SW Atlantic coast. Thus, communities developing in more benign conditions, regardless of their low local diversity, may increase biodiversity at a landscape scale by decreasing their similarities.

Verde, M. 2013: Teisseirei barattinia Roselli 1939: the first sphinx moth trace fossil from palaeosols, and its distinct type of wall. Lethaia, Vol. 46, The trace fossil Teisseirei barattinia, found in Cenozoic formations of Uruguay and Argentina, is an elongated chamber recognizable by its depressed cross-section, antechamber, and its multi-layered lining with an inner surface texture composed of densely packed sub-rectangular to sub-triangular pits. Our recent behavioural observations on larval and pupal stages of Sphingidae (Lepidoptera), particularly on Manduca rustica, suggest that Teisseirei barattinia is the pupation chamber of a sphinx moth. Last instar larvae of Manduca rustica, Eumorpha anchemolus and E. labruscae were placed in terraria to observe their burrowing behaviour and to recover pupation chambers. Chambers show depressed or plane convex cross-sections as T. barattinia. The internal surface texture of walls is also similar to that of T. barattinia. The same pattern could be obtained experimentally by pressing the true legs of Manduca rustica larva against plasticine. The multi-layered wall structure, shown by T. barattinia, is a new type of lining for insect trace fossils in palaeosols that result from soil packing combined with discharges of abundant liquid excretion by soft-bodied larvae, as in the case of Manduca rustica. T. barattinia is the first trace fossil documented in palaeosols attributed to sphinx moths and supported by macro and micromorphological comparisons with extant pupation chambers. The shallow emplacement of moth pupation chambers in soils suggests that T. barattinia would be a good indicator of palaeosol upper horizons. □ Multi-layered wall, palaeopedological significance, pupation chambers, sphinx moth, Teisseirei barattinia.

Genise, J.F. & Farina, J.L. 2011: Ants and xenarthrans involved in a Quaternary food web from Argentina as reflected by their fossil nests and palaeocaves. Lethaia, Vol. 45, pp. 411–422. Quaternary (Ensenadan stage‐age) deposits of the Miramar Formation from the Buenos Aires sea coast near Mar del Plata (Argentina) are well known for bearing long horizontal tunnels produced by xenarthrans, either ground sloths or armadillos. Little known is that, in some cases, these palaeocaves cross‐cut social insect nests. Nests of two studied palaeocaves can be attributed to ants based on the presence of abundant ant remains, filling of chambers and organic‐rich linings. Insect remains show part of a food web composed of army ants (Neivamyrmex) preying on leaf‐cutting ants (Acromyrmex), Pheidole and other soil invertebrates. The other main component of this web is represented by the xenarthrans feeding on these ants. The facultative foraging function of xenarthran palaeocaves is supported by the common record of these extended horizontal tunnel systems similar to other subterranean foraging mammals, the presence of insect nests cross‐cut by them and the extended myrmecophagy among xenarthrans. Xenarthran foraging burrows, despite their high‐energy cost, would have been favoured by abundance of underground ant nests during Quaternary times and harsh climate. This climate would have produced the scarcity of insects on surface and longest periods of underground activity by xenarthrans, involving the extension of shelter burrows for adult and possibly juvenile feeding. □Ant fossil nests, Argentina, Buenos Aires, food web, Quaternary, xenarthran palaeocaves.

A new type of trace fossil from the Lower Cretaceous of Patagonia that may record the oldest evidence of insect agriculture is represented by biconvex, sub-spherical, carbonate balls composed of a dense mass of rhizoliths. The best preserved balls show an external wall, a tunnel entrance, and vertical, large rhizoliths crossing from top to base, from which a mass of smaller rhizoliths arise. In some cases there is a pelletal surface texture in internal layers of the wall. Some specimens show meniscate tubes attributed to organisms different than the constructors of the chambers, probably attracted by the original organic matter. Micromorphology, analyzed by thin sections and SEM, shows strong evidence of high fungal activity associated to the original roots. Four different hypotheses are analyzed to explain the origin of the balls. The less probable ones are either that the balls were produced only by a self induced and localised overgrowth of secondary and tertiary rootlets from a group of neighbouring primary roots, or that they were crayfishes' feeding chambers. Rhizolith arrangement, as well as other characters, essentially rule out both hypotheses. The hypotheses involving social insects, termites and ants, are more risky, considering the lack of support from the body fossil record, the biogeography of these extant insects, and particularly the lack of definitive evidence of discrete fungus or bacterial gardens in the balls. However, the trace fossils described herein partially resemble the nests and behaviour of the African termite Sphaerothermes sphaerothorax, particularly because of the presence of roots inside a thick lined chamber excavated around them to cultivate bacterial combs. The ant origin of these balls is at least a hypothesis to explore considering the size, shape, wall, entrance tunnel, presence of traces of associated organisms, and particularly roots. The roots and wall relate these balls to hypothesised scenarios for the origin of fungus agriculture in ants. One hypothesis suggests that primitive Attini developed fungus agriculture from the habit of feeding on fungi associated with roots (mycorrhizae) and still other proposes that adventitious fungi on nest walls were responsible for the arise of fungiculture. The balls would supply physical evidence that by the lower Cretaceous some social insects excavated chambers around uncut roots, which in turn provided optimal conditions for fungi development. These rhizolith balls possibly constitute the oldest physical evidence for the origin of fungiculture in social insects, and represent a critical contribution of ichnology to this hot topic intensively discussed on the basis of a scattered body fossil record and molecular phylogeny.